scholarly journals Effect of radial impeller size in the presence and absence of baffles on the copper exchange on zeolite NaX

2021 ◽  
Vol 41 (2) ◽  
Author(s):  
Sandra Svilović ◽  
Marija Ćosić ◽  
Anita Bašić
Keyword(s):  
Power Consumption ◽  
Batch Reactor ◽  
Copper Ion ◽  
Impeller Speed ◽  
Zeolite Nax ◽  
Mixing Parameters ◽  
Initial Stage ◽  
Zeolite Particle ◽  
Exchange Kinetics ◽  
Copper Exchange

Effect of hydrodynamics on ion exchange in a batch reactor is still not appropriately studied even though proper mixing parameters may considerably affect the process of solid suspension and its costs. In this work, hydrodynamic conditions generated by straight blade turbine (SBT) impellers on suspension in the batch reactor with and without baffles were investigated. The aim of this work was to analyze influence of impeller diameter and zeolite mass on just suspended impeller speed, (NJS) power consumption, maximum amount of copper exchanged onto zeolite NaX and copper exchange kinetics as well. All experiments were conducted at the same temperature, initial concentration of the copper solution and zeolite particle size. The obtained results showed that just suspended impeller speed decreases as impeller diameter increases in the reactor with and without baffles but this trend is considerably more pronounced in the reactor with baffles. The increase in zeolite mass causes a slight increase of NJS in the both reactor. In the reactor with the baffles this increment became noticeably higher as impeller diameter decrease. Power consumption, at the state of complete zeolite suspension, decreases as impeller diameter increases and its values in the reactor without baffles are considerably lower as well. Kinetics results indicated that the amount of copper ion increases significantly in the initial stage and then gradually until the equilibrium is reached for all hydrodynamics conditions and mass of zeolite examined.

Gas–solid exchange reactions: Zinc vapor and polycrystalline zinc selenide

1968 ◽  
Vol 46 (10) ◽  
pp. 1621-1624 ◽  
Author(s):  
E. A. Secco ◽  
Chien-Huo Su
Keyword(s):  
Zinc Selenide ◽  
Static System ◽  
Zinc Vapor ◽  
Exchange Reactions ◽  
Polycrystalline Zinc ◽  
Diffusion Controlled ◽  
Initial Stage ◽  
Exchange Kinetics ◽  
Kinetics Of ◽  
Exchange Data

The exchange kinetics of zinc vapor with polycrystalline zinc selenide have been studied in a static system in the temperature range 720–800 °C.The kinetic data are consistent with a diffusion-controlled process from the initial stage, in contrast with existing exchange data on ZnO and ZnS powders. The diffusion equation is given as:[Formula: see text]

Enzymatic production of cellulose nanofibers and sugars in a stirred-tank reactor: determination of impeller speed, power consumption, and rheological behavior

Cellulose ◽  
2018 ◽  
Vol 25 (8) ◽  
pp. 4499-4511 ◽  
Author(s):  
Thalita J. Bondancia ◽  
Luciano J. Corrêa ◽  
Antonio J. G. Cruz ◽  
Alberto C. Badino ◽  
Luiz Henrique C. Mattoso ◽  
...  
Keyword(s):  
Power Consumption ◽  
Rheological Behavior ◽  
Cellulose Nanofibers ◽  
Stirred Tank ◽  
Impeller Speed ◽  
Enzymatic Production ◽  
Stirred Tank Reactor ◽  
Tank Reactor

scholarly journals Computational fluid dynamics simulation of solid-liquid suspension characteristics in a stirred tank with punched circle package impellers

2020 ◽  
Vol 18 (9) ◽  
Author(s):  
Deyin Gu ◽  
Mei Ye ◽  
Zuohua Liu
Keyword(s):  
Fluid Dynamics ◽  
Power Consumption ◽  
Solid Particle ◽  
Particle Diameter ◽  
Solid Particles ◽  
Stirred Tank ◽  
Impeller Speed ◽  
Particle Suspension ◽  
Liquid Suspension ◽  
Solid Liquid

AbstractSolid-liquid suspension characteristics in a stirred tank with four pitched-blade impellers, circle package impellers, and punched circle package impellers were studied via computational fluid dynamics (CFD) simulation. A classical Eulerian-Eulerian approach coupled with the standard k-ε turbulence model was adopted to simulate the solid-liquid two-phase turbulent flow. The effects of impeller speed, power consumption, impeller type, aperture size/ratio, solid particle diameter and liquid viscosity on the solid particle suspension quality were investigated. Results showed that the solid particle suspension quality was improved with an increment in the impeller speed. Punched circle package impeller could reduce the just suspension speed and improve the level of homogeneity for solid-liquid mixing process on the basis of four pitched-blade impeller and circle package impeller. The optimum aperture ratio and aperture diameter were 11.8% and 8 mm, respectively, for solid particles suspension process in this work. Smaller particle diameter led to smaller settling velocity and higher solid particle suspension quality. More viscous liquid was easier for sustaining the solid particles in suspension state. Meanwhile, punched circle package impeller can reduce the power consumption compared with four pitched-blade impeller and circle package impeller at the same impeller speed, and enhance the solid integrated velocity, turbulent kinetic energy, and turbulent kinetic energy dissipation rate of solid-liquid mixing system at the same power consumption.

scholarly journals Driving Waveform Design with Rising Gradient and Sawtooth Wave of Electrowetting Displays for Ultra-Low Power Consumption

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 145 ◽  
Author(s):  
Wei Li ◽  
Li Wang ◽  
Taiyuan Zhang ◽  
Shufa Lai ◽  
Linwei Liu ◽  
...  
Keyword(s):  
Power Consumption ◽  
Low Power ◽  
Driving Voltage ◽  
Ultra Low Power ◽  
Sawtooth Wave ◽  
Aperture Ratio ◽  
Initial Stage ◽  
Display Technology ◽  
Three Stages ◽  
Driving Waveform

As a kind of paper-like display technology, power consumption is a very important index for electrowetting displays (EWDs). In this paper, the influence of driving waveforms on power consumption of the EWDs is analyzed, and a driving waveform with rising gradient and sawtooth wave is designed to reduce the power consumption. There are three stages in the proposed driving waveform. In the initial stage, the driving voltage is raised linearly from the threshold to the maximum value to reduce the invalid power consumption. At the same time, the oil breakup can be prohibited. And then, a section of sawtooth wave is added for suppressing oil backflow. Finally, there is a section of resetting wave to eliminate the influence of charge leakage. Experimental results show that the power consumption of the ultra-low power driving waveform is 1.85 mW, which is about 38.13% lower than that of the conventional used square wave (2.99 mW), when the aperture ratio is 65%.

Effects of fill modes on N2O emission from the SBR treating domestic wastewater

2001 ◽  
Vol 43 (3) ◽  
pp. 147-150 ◽  
Author(s):  
K. Y. Park ◽  
J. W. Lee ◽  
Y. Inamori ◽  
M. Mizuochi ◽  
K. H. Ahn
Keyword(s):  
Sequencing Batch Reactor ◽  
Emission Rate ◽  
Batch Reactor ◽  
Domestic Wastewater ◽  
N2o Emission ◽  
Ammonia Nitrogen ◽  
High Concentration ◽  
N2o Production ◽  
Initial Stage ◽  
Biological Nitrogen

Nitrous oxide (N2O) gas is emitted as an intermediate in the biological nitrogen removal process. A track study was performed to investigate the characteristics of N2O emission depending on the cyclic mode of a sequencing batch reactor (SBR). A major emission of N2O took place at the aerobic phase, while N2O emission at the anoxic phase was insignificant. Especially, the highest N2O emission rate was observed at the initial stage of aerobic phase under the limited dissolved oxygen (DO) condition. Under such a condition, nitrite (NO2-) was transiently accumulated along with significant N2O emission due to incomplete nitrification. In addition, N2O production at the aerobic phase was strongly related with incomplete denitrification by nitrifiers. N2O emission could be reduced by change in fill modes in the SBR. A significant conversion to N2O took place in the SBR with the anoxic fill mode, while only small amount of N2O was conversed in the SBR with the aerobic fill mode. Relatively high concentration of ammonia nitrogen (NH4+) accelerated N2O production at the aerobic phase in the SBR with the anoxic fill compared to the aerobic fill. For control of N2O emission in the SBR, the aerobic fill mode could be an effective method even if denitrification efficiency may be reduced at the anoxic phase.

scholarly journals Properties of Surface Heating Textile for Functional Warm Clothing Based on a Composite Heating Element with a Positive Temperature Coefficient

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 904
Author(s):  
Han Na Choi ◽  
Seung Hyun Jee ◽  
Jaehwan Ko ◽  
Dong Joo Kim ◽  
Sun Hee Kim
Keyword(s):  
Power Consumption ◽  
Surface Temperature ◽  
Temperature Coefficient ◽  
Heat Generation ◽  
Rapid Heating ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Initial Stage ◽  
Power Application ◽  
Warm Clothing

A high-stretch positive temperature coefficient (PTC) surface heating textile (PTC-SHT) was fabricated using a composite of PTC powder and multiwall carbon nanotubes (MWCNTs). The PTC-SHT (heating area = 100 × 100 mm2) was produced by screen-printing the PTC-MWCNT composite paste onto a high-stretch textile with embroidered electrodes. Overall, the temperature increased to 56.1 °C with a power consumption of 5 W over 7 min. Subsequently, the surface temperature of the PTC-SHT remained constant despite the continued decrease in power consumption. This indicated that heating was accompanied by an increase in resistance of the PTC-SHT, which is typical of this process—i.e., heating to a constant temperature under a constant voltage over an extended period of time. In addition, 4.63 W power was required to heat the PTC-SHT surface from an external temperature of 5 to 45 °C in 10 min, after which stable low-temperature heat generation behavior was observed at a constant temperature of 50 °C, which was maintained over 40 min. In contrast, negative temperature coefficient (NTC) behavior has been observed in an NTC-SHT consisting of only MWCNTs, where a slow heating rate in the initial stage of power application and a continuous increase in surface temperature and power consumption were noted. The PTC-SHT consumed less power for heat generation than the NTC-SHT and exhibited rapid heating behavior in the initial stage of power application. The heat generation characteristics of the PTC-SHT were maintained at 95% after 100,000 cycles of 20% stretch–contraction testing, and the heating temperature remained uniformly distributed within ± 2 °C across the entire heating element. These findings demonstrated that an SHT with PTC characteristics is highly suitable for functional warm clothing applications that require low power consumption, rapid heating, stable warmth, and high durability.

scholarly journals Physical Modelling of Aluminum Refining Process Conducted in Batch Reactor with Rotary Impeller

Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 726 ◽  
Author(s):  
Mariola Saternus ◽  
Tomasz Merder
Keyword(s):  
Liquid Metal ◽  
Flow Rate ◽  
Batch Reactor ◽  
Physical Modelling ◽  
Processing Parameters ◽  
Refining Process ◽  
Impeller Speed ◽  
Water Model ◽  
Aluminum Production ◽  
Gas Dispersion

The refining process is one of the essential stages of aluminum production. Its main aim is to remove hydrogen, that causes porosity and weakens the mechanical and physical properties of casting aluminum. The process is mainly conducted by purging inert gas through the liquid metal, using rotary impellers. The geometry of the impellers and the processing parameters, such as flow rate of gas and rotary impeller speed, influence the gas dispersion level, and therefore the efficiency of the process. Improving the process, and optimization of parameters, can be done by physical modelling. In this paper, the research was carried out with the use of a water model of batch reactor, testing three different rotary impellers. Varied methods were used: visualization, which can help to evaluate the level of dispersion of gas bubbles in liquid metal; determination of residence time distribution (RTD) curves, which was obtained by measuring the conductivity of NaCl tracer in the fluid; and indirect studies, completed by measuring the content of dissolved oxygen in water to simulate hydrogen desorption. The research was carried out for different processing parameters, such as flow rate of refining gas (5–25 L·min−1) and rotary impeller speed (3.33–8.33 s−1). The obtained results were presented graphically and discussed in detail.

scholarly journals Effect of Impeller Shape on Solid Particle Suspension

2013 ◽  
Vol 34 (1) ◽  
pp. 139-152 ◽  
Author(s):  
František Rieger ◽  
Tomáš Jirout ◽  
Dorin Ceres ◽  
Pavel Seichter
Keyword(s):  
Power Consumption ◽  
Solid Particle ◽  
Solid Particles ◽  
Impeller Speed ◽  
Particle Suspension ◽  
Particle Sizes ◽  
Wide Range ◽  
Pitched Blade Turbine ◽  
Suspension Measurements

Abstract This paper deals with the effect of impeller shape on off-bottom particle suspension. On the basis of numerous suspension measurements, correlations are proposed for calculating the just-suspended impeller speed for a standard pitched four-blade turbine and three types of hydrofoil impellers produced by TECHMIX for several particle sizes and for a wide range of particle concentrations. The suspension efficiency of the tested impellers is compared with the efficiency of a standard pitched blade turbine on the basis of the power consumption required for off-bottom suspension of solid particles. It is shown that the standard pitched blade turbine needs highest power consumption, i.e. it exhibits less efficiency for particle suspension than hydrofoil impellers produced by TECHMIX.

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